The present invention is directed to a door closure mechanism for securing a door in an opening provided in a wall of a vessel to seal the opening against pressure on either side of the door. The mechanism is particularly suitable for use on doors of undersea vessels.
Various door closure mechanisms have been devised for locking a door in an opening provided in vessels, tanks or chambers of various types in a manner which provides a pressure tight seal.
Vessels such as pressure chambers, retorts and the like, require seals which are designed to be outwardly effective, that is effective in the direction of from the inside to the outside of the vessel, while other vessels, such as vacuum chambers and the like, require seals that are inwardly effective, that is effective in the direction of from the outside to the inside of the vessel. In vessels useful in undersea manuevers, such as diving chambers, diver lock-out modules and other types of submersibles, the joint between the opening provided in the vessel wall and the door must be sealed against pressure exerted from either side of the door.
The various door closure mechanisms presently used to secure a door on a vessel wall opening, such as disclosed in U.S. Pat. Nos. 2,219,137 to Moon, 2,355,475 to Skaller and 2,447,464 to Jenkins are of complex design. Such as door is normally of a circular configuration to give it added strength and rigidity to withstand the various forces exerted thereon, has a convex side protruding into the interior of the vessel, and has a rotatable shaft axially mounted on it. The shaft extends outwardly beyond the boundary of the vessel walls to provide sufficient movement of a spider assembly connected to the shaft to effect locking and unlocking and may extend inwardly beyond the convex surface to permit opening and closing from within the vessel. To effect locking, the spider hub of the assembly is required to move towards the door body to thereby actuate a series of lever arms or a series of combinations of lever arms to outwardly extend a locking device located at the junction of the periphery of the door and the vessel wall. The spider assembly may be designed with a series of lever arms attached to the hub, such as by a ball and socket arrangement, in a manner such that relative rotation between the hub and the shaft forces the levers to slide through a series of guides and mountings to engage keeper bars mounted on the vessel wall.
The known closure mechanisms have the drawback of being of a fairly complex design and requiring space outside of the boundaries of the vessel walls for movement of the hub. In the case of undersea operations such protrusions beyond the vessel wall boundary create hazards in that such protrusions can entangle the vessel's life support umbilical cords and the like.
Further, known closure mechanisms present a hazard to the occupants within the chamber of the vessel by the protrusion of the door and the shaft into the chamber.
Still further, the known complex mechanisms ar susceptible to breakdown and malfunctioning which may abort the mission for which the vessel was intended.